Single-layer and multilayer graphene, method of manufacturing the same, object including the same, and electric device including the same
Graphene is formed with a practically uniform thickness on an uneven object. The object is immersed in a graphene oxide solution, and then taken out of the solution and dried; alternatively, the object and an electrode are immersed therein and voltage is applied between the electrode and the object used as an anode. Graphene oxide is negatively charged, and thus is drawn to and deposited on a surface of the object, with a practically uniform thickness. After that, the object is heated in vacuum or a reducing atmosphere, so that the graphene oxide is reduced to be graphene. In this manner, a graphene layer with a practically uniform thickness can be formed even on a surface of the uneven object.
1. A battery comprising:
an active material layer comprising a plurality of whiskers comprising a first whisker and a second whisker; and
one or a plurality of graphene layers covering the plurality of whiskers, and
wherein a part of the one or the plurality of graphene layers connects the first whisker to the second whisker.
2. The battery according to claim 1 , wherein the active material layer is a negative electrode active material layer.
3. The battery according to claim 1 , wherein the one or each of the plurality of graphene layers includes at least one pore.
4. The battery according to claim 1 , further comprising a layer comprising a material different from graphene, the layer being provided over the one or the plurality of graphene layers.
5. The battery according to claim 1 , wherein each of the plurality of whiskers comprises silicon.
6. The battery according to claim 1 , wherein a thickness of the plurality of graphene layers is substantially uniform.
7. An electric device comprising the battery according to claim 1 .
8. The battery according to claim 1 ,
wherein a depression between the first whisker, the second whisker, and the part of the one or the plurality of graphene layers comprises a space.
9. The battery according to claim 1 ,
wherein number of layers of the one or the plurality of graphene layers is 50 or less,
wherein a direction of the plurality of whiskers is random,
wherein a concentration of elements other than carbon and hydrogen contained in the one or the plurality of graphene layers is lower than or equal to 15 atomic %, and
wherein a concentration of oxygen contained in the one or the plurality of graphene layers is higher than or equal to 5 atomic % and lower than or equal to 15 atomic %.
10. An electrode comprising:
a current collector;
an active material layer over the current collector, the active material layer comprising:
a plurality of whiskers comprising silicon the plurality of whiskers comprising a first whisker and a second whisker; and
one or a plurality of graphene layers covering the plurality of whiskers,
wherein a part of the one or the plurality of graphene layers connects the first whisker to the second whisker.
11. The electrode according to claim 10 , wherein the one or each of the plurality of graphene layers includes at least one pore.
12. The electrode according to claim 10 , further comprising a layer comprising a material different from graphene, the layer being provided over the one or the plurality of graphene layers.
13. The electrode according to claim 10 , wherein a thickness of the plurality of graphene layers is substantially uniform.
14. An electric device comprising the electrode according to claim 10 .
15. The electrode according to claim 10 , wherein the one or the plurality of graphene layers is provided over a surface of the current collector and a surface of the plurality of whiskers.
16. The electrode according to claim 10 ,
wherein a depression between the first whisker, the second whisker, and the part of the one or the plurality of graphene layers comprises a space.
17. The electrode according to claim 10 ,
wherein number of layers of the one or the plurality of graphene layers is 50 or less,
wherein a direction of the plurality of whiskers is random,
wherein a concentration of elements other than carbon and hydrogen contained in the one or the plurality of graphene layers is lower than or equal to 15 atomic %, and
wherein a concentration of oxygen contained in the one or the plurality of graphene layers is higher than or equal to 5 atomic % and lower than or equal to 15 atomic %.
18. The battery according to claim 9 , wherein the number of layers of the one or the plurality of graphene layers is 20 or less.
19. The electrode according to claim 17 , wherein the number of layers of the one or the plurality of graphene layers is 20 or less.